MN-166 (also known as ibudilast) is an investigational drug being developed by MediciNova to treat amyotrophic lateral sclerosis (ALS) and other neurological conditions, such as progressive multiple sclerosis, as well as a possible treatment for substance abuse and addiction.
How does MN-166 work?
MN-166 is a compound that inhibits enzymes called phosphodiesterase (PDE)-4 and -10, and the macrophage migration inhibitory factor (MIF). These enzymes are present in central nervous system (CNS) and immune cells that cause a broad spectrum of inflammatory effects, which can lead to nerve cell death (neurodegeneration).
MN-166 suppresses pro-inflammatory cytokines, or signaling molecules that regulate the immune response and inflammation. MN-166 also attenuates activated glia cells, which are major players in neurological conditions.
The drug is being developed as an oral treatment, and its anti-neuroinflammatory and neuroprotective actions have already been demonstrated in earlier clinical studies, for example in multiple sclerosis.
A Phase 2 study (NCT02238626) testing MN-166 is ongoing but not recruiting participants. It is a single-center, randomized, double-blind, and placebo-controlled study designed to evaluate the safety, tolerability, and clinical responsiveness of MN-166. During the trial, 60 mg of the drug per day is being administered, along with 100 mg each day of riluzole (brand name, Rilutek), to about 60 early and advanced-stage ALS patients.
The six-month double-blind study will be followed by a six-month open-label phase for participants taking placebo.
Patients will be checked either by phone or with visits to the clinic to collect information about potential side effects of the treatment, and the use of other medication. All participants (even those who prematurely discontinue the treatment) will have a follow-up visit approximately two weeks after the last dose.
The trial’s primary objective is to evaluate the safety and tolerability of MN-166 compared to placebo when administered with riluzole in people with ALS.
In addition to judging the treatment’s safety and tolerability, researchers will be measuring ALS burden using an ALS functional scales that assess upper or lower motor neuron weakness, and change in respiratory function.
An exploratory interim analysis of 47 patients found significant decreases in muscle strength two weeks after stopping the MN-166 treatment for hip, leg and neck flexion. Lower-motor-neuron ALS burden significantly deteriorated in limb-onset patients, but significant changes were not seen in bulbar-onset patients. (In bulbar-onset ALS, patients first experience symptoms in the head and neck, including trouble speaking or swallowing.) The results were presented at the American Academy of Neurology Annual Meeting in Boston in April 2017.
Next steps for MN-166
According to Dr. Benjamin Brooks, the director of Carolinas HealthCare System’s Neuromuscular/ALS-MDA Center, future clinical trials could target bulbar-onset ALS patients. New clinical trial designs may also identify other groups of people with ALS who respond to a treatment like MN-166.
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